EPA: South Bay sewage plant expansion contract awarded, river gates under construction

The U.S. Environmental Protection Agency says work on the Tijuana River sewage crisis reached several milestones over the summer, according to a quarterly update it released Sept. 30.

The agency says the Parallel Gravity Line was finished in August, and construction on Phase 2 of the river’s diversion gates began in September, with completion expected in early 2027. In September, EPA also awarded the first major construction contract to expand primary treatment at the South Bay International Wastewater Treatment Plant to 50 million gallons a day; the plant reached 35 million gallons a day in August 2025. Crews cleared about 16,622 feet of the river’s pilot channel ahead of the rainy season.

On the Mexican side, EPA reports progress on four sewer interceptor and collector projects, three targeted for completion in December 2026 and one in July 2027. The agency also says flows from canyon collectors are down 97% and exceedances at the plant are down 99%. Those figures come from EPA and have not been independently verified.

The update arrived days after county health officials again closed the Imperial Beach shoreline because river water carrying sewage was reaching the ocean.